U.S. patent number 8,167,231 [Application Number 12/316,201] was granted by the patent office on 2012-05-01 for shielding arrangement for lines, in particular electrical lines, in aircraft.
This patent grant is currently assigned to Airbus Deutschland GmbH. Invention is credited to Frank Falow, Holger Frauen, Volker Leisten.
United States Patent |
8,167,231 |
Leisten , et al. |
May 1, 2012 |
Shielding arrangement for lines, in particular electrical lines, in
aircraft
Abstract
A shielding arrangement for the lightning protection of
electrical lines and components in an aircraft includes a protected
installation space for receiving the lines that is arranged in the
region of a floor framework, at least one delimiting surface of the
installation space being provided at least in certain regions with
an electrically conductive shielding, the at least one delimiting
surface of the installation space being formed with at least one
floor panel and a further delimiting surface of the installation
space being formed with at least one ceiling panel.
Inventors: |
Leisten; Volker (Wedel,
DE), Falow; Frank (Buxtehude, DE), Frauen;
Holger (Hamburg, DE) |
Assignee: |
Airbus Deutschland GmbH
(Hamburg, DE)
|
Family
ID: |
40875689 |
Appl.
No.: |
12/316,201 |
Filed: |
December 10, 2008 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20090184199 A1 |
Jul 23, 2009 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
61008692 |
Dec 21, 2007 |
|
|
|
|
Current U.S.
Class: |
244/1A |
Current CPC
Class: |
B64C
1/18 (20130101); B64D 45/02 (20130101) |
Current International
Class: |
B64D
45/00 (20060101) |
Field of
Search: |
;244/1A,117R,119,118.5,118.6,133,121 ;174/384 ;361/218,816 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
102 23 840 |
|
Dec 2003 |
|
DE |
|
0 588 174 |
|
Mar 1994 |
|
EP |
|
0 835 049 |
|
Sep 1997 |
|
EP |
|
Other References
Office action cited in corresponding DE application 10 2007 061
111.8. cited by other.
|
Primary Examiner: Barefoot; Galen
Attorney, Agent or Firm: Greer, Burns & Crain, Ltd.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application
No. 61/008,692, filed Dec. 21, 2007, the entire disclosure of which
is herein incorporated by reference.
Claims
What is claimed is:
1. An electromagnetic shielding arrangement for the lightning
protection of electrical lines and components in an aircraft, the
electromagnetic shielding arrangement comprising: a protected
installation space for receiving the lines, that is arranged in the
region of a floor framework, and at least one delimiting surface of
the protected installation space being provided at least in regions
with an electrically conductive shielding, wherein the at least one
delimiting surface of the protected installation space is formed
with at least one floor panel and a further delimiting surface of
the protected installation space is formed with at least one
ceiling panel, and wherein the floor panels and the ceiling panels
are configured as sandwich panels, comprising electrical conductive
shielding over their full surface area, and on both sides.
2. The shielding arrangement according to claim 1, wherein the
least one delimiting surface is formed in a planar manner, and
curved at least in one direction of the space.
3. The shielding arrangement according to claim 1, wherein the at
least one delimiting surface encloses the installation space
completely.
4. The shielding arrangement according to claim 1, wherein the
electrical conductivity of the shielding varies from region to
region.
5. The shielding arrangement according to claim 1, wherein
electrically conductive shielding is insulated at least in certain
regions.
6. The shielding arrangement according to claim 1, wherein the
electrically conductive shielding is connected to a central
earthing system of the aircraft.
7. The shielding arrangement according to claim 1, wherein the
electrically conductive shielding serves as a return conductor for
onboard electrical systems.
8. The shielding arrangement according to claim 1, wherein the
floor panels are fixed on transverse beams of the floor framework
and the ceiling panels are fixed under the transverse beams by
fastening elements.
9. The shielding arrangement according to claim 8, wherein the
fastening elements are electrically conductive fastening
screws.
10. The shielding arrangement according to claim 1, wherein the
electrically conductive shielding is formed with a metal foil,
metallic vapour deposition, metallization, a woven metal fabric, a
nonwoven metal fabric, an electrically conductive plastics
material, and any combination thereof.
11. The shielding arrangement according to claim 8, wherein the
transverse beams are formed with an electrically conductive
material.
12. The shielding arrangement according to claim 11, wherein the
transverse beams are formed with at least one of an aluminum alloy
material and a CRP material.
13. The shielding arrangement according to claim 1, wherein seat
rails formed with an electrically conductive material are arranged
on the transverse beams.
14. The shielding arrangement according to claim 13, wherein the
seat rails are formed of at least one of an aluminum alloy material
and a titanium alloy material.
15. The shielding arrangement according to claim 1, wherein the
electrically conductive shielding of the floor panels and the
ceiling panels is debossed through, at least on one side, in the
region of fastening bores, to create an electrically conductive
connection between transverse beams, floor panels, ceiling panels
and seat rails.
Description
FIELD OF THE INVENTION
The invention relates to a shielding arrangement, in particular for
the lightning protection of electrical lines and components in
aircraft, having a protected installation space for receiving the
lines that is arranged in particular in the region of a floor
framework.
BACKGROUND OF THE INVENTION
In aircraft construction, composite materials, in particular carbon
fiber reinforced epoxy resins (CRP material), are increasingly
being used for the production of wings, vertical and horizontal
tail surfaces and for fuselage cells of aircraft. As a result of
the considerably reduced electrical conductivity in comparison with
conventional aluminum fuselages of a fuselage cell that is produced
for example with a CRP material, there is reduced protection of the
onboard electrical systems within the aircraft, which are generally
highly sensitive, with respect to external electromagnetic
disturbances. These external electromagnetic disturbances are, for
example, lightning strikes, radio waves and radar waves with a high
field strength or the like. In addition, sources of electromagnetic
interference may also be present within the fuselage cell of an
aircraft itself, such as for example passengers' telecommunications
equipment or portable data-processing systems, which often emit
high-frequency and pulsed electromagnetic radiation. Therefore, all
installations must be implemented in such a way that the sensitive
onboard electrical and electronic systems, in particular the flight
computer, the electronic control systems for the active aerodynamic
areas of the aircraft, electrical emergency systems and the engine
control are not impaired in their function in any way by such
disturbances.
To minimize the interference of such onboard electrical systems by
such electromagnetic disturbances, a large number of measures are
widely taken. For example, twisted-together forward and return
conductors or laying of lines in the vicinity of metal structures,
such as for example on seat rails, stringers, ring frames or the
like, may be used for the cabling of the onboard electrical systems
of the aircraft. Furthermore, to achieve a particularly good
shielding effect, metal meshes are used for enclosing the
electrical lines and/or metal cable ducts in which the unshielded
lines run. All the measures may be used on their own or in
combination with one another. Both the shielding meshes, which are
for example pulled over the lines from the outside in the form of
net-like tubes, and the metal cable ducts always lead to a
considerable extra weight of the overall cabling--quite apart from
increased installation effort and a restriction of the laying paths
available. In addition, the shielding meshes and the metal cable
ducts make subsequent modification of the electrical installation
more difficult. Furthermore, additional, generally
weight-increasing, measures have to be taken in the cable ducts to
avoid impairment of the mechanical integrity of the insulation of
the lines, for example in the form of chafing through. However, the
use of twisted conductor arrangements and/or laying in the vicinity
of metal structures in the aircraft is often unsatisfactory with
respect to the achievable degree of the electromagnetic protective
effect, or means increased restriction on routing. On the other
hand, direct integration of an electromagnetically fully effective
protective mesh in the CRP fuselage cell of the aircraft would
largely nullify the weight advantages of the composite
material.
On account of the disadvantages of the known shielding measures for
electrical lines set out above, they are only recommendable with
reservations for use in aircraft with CRP fuselages.
SUMMARY OF THE INVENTION
One of the objects of the invention is therefore to avoid the
disadvantages described above of the known embodiments of
shieldings of lines in aircraft from sources of electromagnetic
disturbance.
Accordingly, a shielding arrangement for the lightning protection
of electrical lines and components in an aircraft comprises a
protected installation space for receiving the lines that is
arranged in the region of a floor framework, at least one
delimiting surface of the installation space being provided at
least in certain regions with an electrically conductive shielding,
the at least one delimiting surface of the installation space being
formed with at least one floor panel and a further delimiting
surface of the installation space being formed with at least one
ceiling panel. The at least one delimiting surface may be formed
with a plurality of floor panels and the further delimiting surface
may be formed with a plurality of ceiling panels.
The fact that at least one delimiting surface of the installation
space is provided at least in certain regions with an electrically
conductive shielding produces effective shielding of a large-volume
installation space for lines, in particular electrical lines, and
other items of equipment or components, with respect to external
electromagnetic disturbance fields, with at the same time low
additional weight, since components that are present in any case in
the fuselage cell, such as for example floor panels, ceiling lining
panels, lining elements or other structural elements, can also be
used as a delimiting surface to define the installation space. At
the same time, other physical properties of the components within
the fuselage cell, such as for example their mechanical strength or
their burning-through characteristics, can be specifically
optimized by the shielding.
The components or items of equipment that are protected by the
installation space may be any electronic and/or electrical devices
or else metal pipelines, compartments or the like, since the
electromagnetic fields that interfere with metal pipelines for
oxygen or water, for example, can likewise induce high voltages,
which can lead to spark formation with the risk of explosion or to
sparkovers and disruptive discharges.
In addition, installation of the electrical line systems in a
fuselage cell of an aircraft is made considerably easier, since
there is no longer any need for shielding meshes or shielding tubes
for enclosing the lines, metal cable ducts or special forms of
cable with twisted conductor arrangements. Previously existing
restrictions with respect to the laying paths or line routing to be
maintained, for example in the form of the requirement not to allow
sensitive lines to run or be grouped in the vicinity of
electrically conductive components in the fuselage cell in order to
improve the immunity to interference, no longer need to be
observed. Rather, the lines to be protected can be placed almost at
will in the installation space and, if required, fixed in their
position there. Conventional line laying without special shielding
measures is generally entirely adequate. Any crosstalk between
parallel running electrical lines within the installation space is
avoided by the safety distances between the respective cables that
are defined in any case. Measures beyond this for electromagnetic
shielding are no longer required.
One embodiment of the shielding arrangement provides that the at
least one delimiting surface is formed in a planar manner and/or
curved at least in one direction of the space.
As a result, a space-saving adaptation of the shielded installation
space for the protection of the electrical lines to the spatial
conditions available is possible, which is of significance in
particular in the case of the generally very confined space
conditions within aircraft fuselage cells.
In accordance with a further configuration of the shielding
arrangement, the at least one delimiting surface encloses the
installation space as completely as possible.
As a result of the substantially completely uninterrupted
delimiting surface, a particularly effective shielding effect of
the installation space and of the electrical lines running in it is
achieved with respect to external electromagnetic disturbance
fields.
According to a further embodiment of the shielding arrangement, the
electrical conductivity of the shielding varies from region to
region.
This configuration makes local adaptation of the shielding effect
to the respective local conditions possible. For example, the
conductivity of the shielding, which is generally correlated with
the layer thickness of the shielding, can be increased in the
region of components that are particularly relevant to safety, in
order to increase the immunity to interference. Moreover, the
weight of the required electrical shielding can be optimized by
local variation of the conductivity.
In accordance with one embodiment of the shielding arrangement, the
electrical conductive shielding is provided at least in certain
regions with an insulating layer.
As a result, impairment of the integrity of the electrical
insulation of the lines running in the installation space, for
example by vibration-induced chafing through and resultant
short-circuits, is avoided.
A further embodiment of the shielding arrangement provides that the
electrically conductive shielding of the installation space is
connected to a central earthing system of the aircraft.
The connection to the central earthing system makes a particularly
effective shielding effect from external disturbing electromagnetic
influences possible, since other electrical devices of the aircraft
are then also connected to the shielding and the central earthing
system.
In accordance with a further embodiment of the shielding
arrangement, it is provided that the electrically conductive
shielding serves as a return conductor for further onboard
electrical systems.
As a result, the number of electrical lines necessary for cabling
an onboard electrical system of an aircraft can be reduced, since a
separate return conductor does not have to be provided for each
line leading to an electrical component. The effect of the
reduction of the required number of lines occurs in particular in
the case of fuselage cells that do not have adequately high
(intrinsic) electrical conductivity (current carrying capacity), as
is the case for example with fuselage cells produced predominantly
with CRP materials or with other fiber reinforced plastics, to
ensure failsafe operation of all the electronic and electrical
components in all operating states of the aircraft occurring.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is explained in more detail below using
preferred exemplary embodiments and with reference to the attached
figures of the drawings, in which:
FIG. 1 shows a cross-sectional representation through a fuselage
cell of an aircraft with a floor framework with an installation
space for lines, in particular electrical lines, arranged in it
that is largely protected from external electromagnetic disturbance
fields,
FIG. 2 shows a perspective oblique view of the floor framework with
the protected installation space, and
FIG. 3 shows a sectional representation through a floor panel or
ceiling panel as a delimiting surface for the protected
installation space.
In the figures, like reference numbers refer to identical or
functionally identical components unless otherwise stated.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic cross section through a fuselage cell of
an aircraft with a protected installation space.
A protected installation space 1 is formed within a floor framework
2. Located substantially perpendicularly to the plane of the
drawing inside the installation space 1, which is symbolized by the
dotted representation of a rectangular outline, are a plurality of
lines and components, in particular electrical lines and
components, of which only three lines 3, 4, 5 are provided with a
reference numeral as representative of the others.
Lines branches that run parallel to the plane of the drawing are
not represented. In addition to the electrical lines, lines of any
type, such as for example hydraulic lines, water and waste-water
lines, ventilating and venting lines, air-conditioning lines or the
like, may be arranged in the installation space 1.
The installation space 1 is closed off in the upward direction by a
delimiting surface 6, which is formed by a plurality of floor
panels 7 substantially adjoining one another. The floor panels 7
are fastened on a metal transverse beam 8 by suitable fastening
elements, such as for example metal screws or rivets, which are not
represented in FIGS. 1, 2. The transverse beam 8 is formed e.g.
with an aluminum alloy material and is connected on both sides to
ring frames of a substantially non-conducting CRP fuselage-cell
structure 9 of an aircraft that is not represented. In a fuselage
cell produced substantially completely with CRP materials, the
transverse beams are also generally produced with CRP materials,
further increasing the necessity for protective measures. The
installation space 1 is in this case particularly advantageously
suitable for receiving electrical lines or cables that run
transversely in relation to the longitudinal axis of the aircraft
and can no longer be arranged in the vicinity of a metal transverse
beam.
Provided under the transverse beam 8 are two supporting rods 10, 11
(Samer rods) for further supporting the transverse beam 8. In the
downward direction, with respect to a cargo hold 12, the protected
installation space 1 is closed off by a further delimiting surface
13, which is formed by a plurality of ceiling panels adjoining one
another--of which only one ceiling panel 14 bears a reference
numeral. Arranged above the floor panels 7 are a plurality of
passenger seats 15 in a passenger compartment 16 of the aircraft.
Both the floor panels 7 and the ceiling panels 14 are provided on
both sides with an electrically conductive shielding that is not
represented in FIGS. 1, 2, in order to create the protected
installation space 1. Both the floor panels 7 and the ceiling
panels 14 are usually sandwich panels with a core structure, for
example of a honeycomb form, of impregnated Nomex.RTM. paper, which
are formed on both sides with outer layers of a fiber reinforced
plastics material. Both outer layers may be provided with
electrically conductive shielding, which may be applied for example
in the form of a metal foil, metallic vapour deposition,
metallization, a woven metal fabric, a nonwoven metal fabric, an
electrically conductive plastics material or any combination
thereof. If the core structure is, for example, a folded honeycomb
core structure, the shielding effect that can be achieved by this
may be adequate, so that it is possible to dispense with a separate
conductive coating of the outer layers of the floor panels 7 and
the ceiling panels 14.
In the region of two substantially triangular interstices 17, 18,
there are no ceiling panels and no lateral shieldings following the
inner contour of the CRP fuselage cell structure, so that the
shielding effect from disturbing electromagnetic radiation
interfering with the protected installation space 1 is reduced. In
a configurational variant that is not shown, additionally arranged
in the region of the interstices 17, 18 are curved shieldings,
which together with the floor panels 7 and the ceiling panels 14
represent a largely uninterrupted, electrically conducting
shielding (substantially closed, electrically conductive enveloping
surface) with a high shielding effect even from disturbing
radiation entering the protected installation space 1 laterally.
FIG. 2 shows a perspective view of the floor framework with the
protected installation space.
The floor panels 7 rest on a plurality of transverse beams, of
which only the front transverse beam 8 is provided with a reference
numeral, while the ceiling panels 14 of the cargo hold 12 are
fastened to or suspended from the underside of the transverse beams
8. The front transverse beam 8 is supported on a ring frame 19 by
means of the Samer rod 10. Both the floor panels 7 and the ceiling
panels 14 are respectively provided on both sides with an
electrically conductive shielding 20, 21. The electrically
conductive shieldings 20, 21 on the floor and ceiling panels 7, 14
may be formed by metal foils, metallic vapour deposition,
metallization, a woven metal fabric, nonwoven metal fiber fabrics,
electrically conductive plastics materials or any combination
thereof. In the case where the floor and ceiling panels are formed
in the sandwich type of construction, the electrically conductive
shielding may, for example, be produced by an electrically
conductive folded honeycomb core, for example a folded honeycomb
produced with a metallized Nomex.RTM. paper. The electrical
conductivity of the shieldings may vary locally, in order if
required to increase the shielding effect of the installation space
1 in the region of lines that are particularly relevant to flight
safety. This may be achieved, for example, by different material
thicknesses of the metallization and/or a combination of different
metals (copper, silver, gold, etc.). Moreover, the shielding 20, 21
allows further physical properties--for example the burning-through
characteristics, the so-called "impact" behaviour, i.e. including
the penetration resistance with respect to parts flying around with
high kinetic energy in the event of engine defects, or the
mechanical strength--of the floor panels 7, the ceiling panels 14
and further components serving for the shielding to be specifically
optimized.
As a result of the electrically conductive shieldings 20, 21
running on the upper side and underside of the protected
installation space 1, external electromagnetic disturbance fields
cannot have a disturbing influence on the electrical lines 3, 4, 5
running in the protected installation space 1. A number of metal
seat rails, running in a longitudinal direction of the CRP fuselage
cell structure and formed for example with an aluminum alloy
material, only one of which is provided with a reference numeral
22, are arranged on the transverse beams of the floor framework 2.
Between the seat rails, which are arranged such that they run
substantially parallel to and at a distance from one another and
serve, inter alia, for fixing the passenger seats 15, the floor
panels 7 are placed and fastened on the transverse beams lying
thereunder. The seat rails 22 and the transverse beams 8 run at an
angle of approximately 90.degree. to one another and together form
the grid-shaped floor framework to create the required support for
the floor panels 7 and the fastening of the passenger seats 15 in
the passenger compartment 16 of the aircraft. At the same time,
this grid itself forms an at least coarsely meshed Faraday's
cage.
To achieve a shielding effect of the protected installation space 1
that is as effective as possible, the floor panels 7, the ceiling
panels 14, the transverse beams 8 and the seat rails 22 are
respectively connected to one another in an electrically conducting
manner by means of suitable metal fastening elements, in particular
by screws, riveted connections, clamped connections or the like.
The components mentioned may be additionally connected to a central
earthing system 24 of the aircraft by respective earthing lines 23.
Furthermore, it is possible to use the electrically conductive
shieldings 20, 21 themselves as return conductors for the lines 3,
4, 5, in order to obviate the need for separate return lines for
current return.
FIG. 3 shows an exemplary cross section through a floor panel for
forming a delimiting surface of the protected installation
space.
A floor panel 25 has a sandwich construction with a core structure
26 and outer layers 27, 28 applied to the core structure 26 on both
sides. Both outer layers 27, 28 are respectively provided with an
electrically conductive shielding 29, 30, for example over the full
surface area. The electrically conductive shielding 29, 30 may, if
required, be formed region by region, have locally different
material thicknesses and be formed locally with different metals or
metal alloys. Both outer layers 27, 28 may be formed, for example,
with a carbon fiber reinforced epoxy resin, a glass fiber
reinforced phenolic resin or other fiber reinforced thermosetting
plastics. The core structure 26 generally has a geometric shape of
a honeycomb form and is formed from Nomex.RTM. paper impregnated
with a phenolic resin, the longitudinal axes of the honeycomb cells
respectively running substantially perpendicularly to the surface
of the panel. Alternatively, fiber reinforced thermoplastics may
also be used for producing the outer layers 27, 28 and/or the core
structure 26.
Serving, for example, for fastening the floor panel 25 on a
transverse beam 31 of a floor framework that is not represented in
FIG. 3 is a cylindrical fastening bore 32 with a frustoconical
countersink 33, in which there is inserted a metal fastening screw
34, which is screwed with a threaded bore 35 in the transverse beam
31. In the region of the frustoconically shaped countersink 33, at
least the upper electrically conductive shielding 29 is "debossed
through", that is to say the shielding 29 extends into the region
of the countersink 33, right up to the cylindrical fastening bore
32. As a result of this configuration, a continuously electrically
conductive contact is created between the shielding 29, the
conductive metal fastening screw 34 and the transverse beam 31,
which is likewise formed for example in an electrically conducting
manner.
The substantially completely uninterrupted shielding surface of the
installation space 1 has the effect that its electrical shielding
effect is further optimized. In principle, fastening elements of
all kinds, such as for example riveted or clamped connections, may
take the place of the metal fastening screw 34, it having to be
ensured however that a contact that is as continuous as possible is
produced between the shielding of the floor panels 25 and the
transverse beams 31 or the seat rail profiles of the floor
framework. The construction of the floor panel 25 described in
detail above substantially corresponds to the construction of a
ceiling panel that is used for lining the ceiling of the cargo hold
12.
One or both electrically conductively formed shieldings 29, 30 may
be provided in certain regions or over the full surface area with
an insulating layer 36, in order for example to prevent the
vibration-induced chaffing through of cable insulations of the
electrical lines 3, 4, 5 laid in the protected installation space 1
(cf. FIGS. 1, 2) and resultant short-circuits.
For the case where a core structure 26 of the floor panel 25,
configured for example as a sandwich panel, is formed in an
electrically conductive manner in order to create an inner
electrically conductive shielding, rivets spreading out in a radial
direction are particularly well-suited for fastening the floor
panel 25 on the transverse beam 31, since an electrical contact
between the then inner shielding and the likewise electrically
conductive transverse beam 31 is created by the rivet widening in a
radial direction during the setting operation. Apart from the floor
panels and ceiling panels, any other components of the fuselage
cell structure of the aircraft may be provided with a
correspondingly configured electrically conductive shielding to
form and/or add further to the protected installation space 1.
As a departure from the exemplary embodiment described, the
installation space 1 may also be used in other regions of the
aircraft in which similar shielding problems occur--presupposing a
corresponding geometric shape. For example, the creation of such
installation spaces is conceivable for installations in what is
known as the "crown area" above the "hat racks" in the region of
the ceiling lining of a passenger aircraft cabin, or else, if
required, in wet cells, such as for example in sanitary or galley
modules.
* * * * *